API 2.0. - Unable to send the PATCH request after a Program was deleted from the Solution Objective

Issue Summary

After a Program was deleted from the Solution Objective, the deleted program is still listed on the GET request. When a user tries to PATCH the  Solution Objective, he/she receives an error "Cannot update the Milestone. Value for Program ID xx is invalid"

Steps to Reproduce

1. Create a Solution Objective
2. Add a Solution with several programs assigned
3. Delete one of the programs
4. Send GET Request
5. Update the Solution Objective with a PATCH request

Expected Results

1) The deleted Program is not listed under the GET request.

2) The user is able to update the Solution Objective  with a PATCH request

Actual Results

1) The deleted Program ID is still available on GET request

2) The user is not able to PATCH the Solution Objective after a program was deleted.

...

Workaround

It is possible to send PUT or POST request after manually removing the deleted Program ID.